we're learning more about the dual explosions that rocked the boston marathon, an iconic event, marred by tragedy. 8:00 on a somber tuesday morning. the 16th of april, 2013. i'm savannah guthrie in new york. and matt has been in boston this morning. >> savannah, good morning again to you. the scene obviously surreal. the runners approaching the finish line after completing more than 2 6 miles of this race. people on the sidelines, family members and loved ones cheering them on. they were lining the streets. and this morning, the fbi is leading an investigation, being called a very fluid and active investigation. we'll have the latest in a couple of minutes. savannah. >> math, also ahead, we'll air part one of the exclusive interview with president obama. sat down with him just hours before the attack in boston. and asked him whether he thinks congress will pass this new gun legislation. hanging by a thread, according to some accounts and how worried is he about the provocative action and rhetoric from the north korean leader, kim jong-un? is he stable? we'll hear from him in our exclus